CA3185492A1 - Hydraulic pressure control valve with pneumatic actuation - Google Patents

Abstract

The invention relates to a hydraulic pressure control valve with pneumatic actuation, compris-ing a valve body, a spool, and a sealing element, wherein the valve body has a first port, a second port, and a third port, the first, second and third ports connected to a first bore of the valve body, and wherein the valve body further has a first control port for sensing a hydraulic liquid and a second control port for receiving a pneumatic gas. The spool is located in the first bore and is movable between a first end position and a second end position, the spool having lands, such that in the first end position the first port and the third port are connected and in the second end position the first port and the second port are connected. The spool has a first end and a second end in axial direction, wherein a first face of the spool near the first end is connected to the first control port, wherein the sealing element is arranged between the second control port and the first bore to seal the second control port from the first bore, and wherein the sealing element is flexible such that movement of a part of the sealing element in axial direction is possible and is coupled to the second end, such that the sealing element is able to exert force onto the spool that effects movement of the spool in direction of the second end position.

Description

Hydraulic pressure control valve with pneumatic actuation Technical Field The present invention relates to a hydraulic pressure control valve with pneumatic actuation.
Background Mobile working machines, such as trucks, excavators or wheel loaders, may have moveable parts that are attached or attachable to the respective machine and whose movement is achieved by means of a hydraulic cylinder or hydraulic motor. Pressurized hydraulic liquid may be provided by a hydraulic pump. Flow of hydraulic liquid to the hydraulic cylinder or hydraulic motor is typically controlled by one or more directional control valves, which direct the flow of hydraulic liquid to and from the hydraulic cylinder or hydraulic motor.
Summary A hydraulic pressure control valve with pneumatic actuation according to the independent claims ist proposed. Advantageous embodiments form the subject matter of the dependent claims and of the subsequent description.
The hydraulic pressure control valve comprises a valve body, a spool, and a sealing element.
The spool is installed (i.e. located or disposed) in a bore (first channel) of the valve body and is movable between a first end position and a second end position. The spool has lands, such that in the first end position a first port and a third port are connected and in the second end position the first port and a second port are connected. The spool has a first end and a second end in axial direction, wherein a first face of the spool near the first end is connected to a first control port (which is configured to receive hydraulic fluid). The sealing element is arranged between a second control port (which is configured to receive hydraulic gas) and the first bore to seal the second control port from the first bore, further, the sealing element is flexible, such that movement of a part of the sealing element in axial direction is possible, and is coupled to the second end, such that the sealing element is able to exert force onto the spool that effects movement of the spool in direction of the second end position. By using a flexible sealing Date Recue/Date Received 2022-12-20 element, such as a membrane, firstly, separation of the parts of the valve, in which hydraulic fluid (e.g. hydraulic oil) is present, from parts of the valve, in which pneumatic gas (e.g. air) is present, is achieved. Secondly, force due to the pneumatic pressure is used to cause move-ment of the spool, such that the flow of hydraulic fluid through the pressure control valve is controlled by the pressure of the pneumatic gas received at the second control port.
As used herein (unless otherwise stated or apparent from the context), the term "connected"
means connected for fluid exchange, i.e. a fluid (such as hydraulic fluid or pneumatic gas) may flow between elements (e.g. ports) that are connected.
Further advantages and embodiments of the invention will become apparent from the descrip-tion and the appended figures.
The invention is shown schematically in the figures on the basis of exemplary embodiments and will be described in the following, with reference to the figures.
Short Description of the Figures Figure 1 shows a hydraulic pressure control valve with pneumatic actuation according to an embodiment.
Figure 2 schematically shows an exemplary system which uses a hydraulic pressure control valve as shown in Figure 1.
Detailed Description Figure 1 shows a hydraulic pressure control valve 2 with pneumatic actuation according to an embodiment. The pressure control valve 2 includes a valve body 4, a spool 6, and a sealing element 8.
In the shown exemplary embodiment, the valve body 4 has three valve body parts 41, 42, 43.
For example, without limitation, the first valve body part 41 and the second valve body part 42 are connected by a press fitting, and the second valve body part 42 and the third valve body part 43 are connected by a threaded fitting. Other numbers of valve body parts and methods

2 Date Recue/Date Received 2022-12-20 of connections are possible as well. Sealing rings (0-rings) may be used to seal the connec-tions between the valve body parts.
The valve body 4 has a first port A, a second port P, and a third port T, which serve as in-let/outlet ports for hydraulic fluid. The valve body 4 has a first control port X1 (first sensing port) for receiving a hydraulic fluid and a second control port X2 (second actuation port / second sensing port) for receiving a pneumatic gas (e.g. air). The first, second, and third ports A, P, T
as well as the first control port X1 are provided in the first valve body part 41, for example. The second control port X2 is provided in the third valve body part 43, for example.
The valve body 4 includes an internal first bore 10 (or first channel) extending in axial direction, in which the spool 6 is supported. The first bore 10 extends through the first and second valve body parts, for example. The first bore 10 and the spool 6 extend in an axial direction of the valve body 4. The first port A, the second port P, and the third port T are connected to the first bore 10 by channels extending in essentially radial direction.
The spool 6 is movable in the first bore 10 in the axial direction between a first end position ( the position shown in the figure) and a second end position. The spool 6 has circumferential lands. In the first end position the first and third ports A, T are connected by means of these lands and the associated spool position (i.e. by means of the circumferential groove between these lands). In the second end position the first and second ports A, P are connected by means of these lands and the associated spool position. That is, in the first end position flow of hydraulic fluid is possible between the first and third ports A, T, and in the second end position flow of hydraulic liquid is possible between the first and second ports A, P. In the first end position the first and second ports A, P are not connected by means of the lands (i.e. no flow of hydraulic fluid is possible between the first and second ports A, P in the first end posi-tion, except for leakage). In the second end position the first and third ports A, T are not con-nected by means of the lands (i.e. no flow of hydraulic fluid is possible between the first and third ports A, T in the second end position, except for leakage).
In the shown embodiment the length of the lands and the distance of the second and third ports P, T from each other (length and distance in axial direction), i.e. the positioning of control edges (control notches), is such that the second and third ports P, T may not be connected to the first port A simultaneously. That is, the second and third ports P, T may not be connected

3 Date Recue/Date Received 2022-12-20 by the lands. It will be appreciated by those skilled in the art that in other embodiments (not shown) the length of the groove and the distance of the second and third ports P, T from each other, i.e. the positioning of control edges, may be arranged, such that in an intermediate po-sition of the spool the second and third ports P, T are connected to the first port A simultane-ously (i.e. the second and third ports P, T may be connected by the lands).
The spool 6 is biased into the first end position by a biasing element, for example a spring 12.
In axial direction, the spool 6 has a first end 18 (first axial end) and a second end 20 (second axial end). The second end 20 is opposite to the first end 18 in an axial direction. A first face 22 of the spool 6 that is near the first end 18 is connected to the first control port X1. The first face 22 is perpendicular to the axial direction and is arranged to receive pressure of hydraulic fluid received at the first control port X1 (or a receiving chamber thereof).
Pressure exerted onto the first face 22 causes a force to move the spool 6 into the direction of the first end position.
The sealing element 8 is flexible such that movement of a part of the sealing element 8 in axial direction is possible. The sealing element 8 may be elastic or resilient, for example. The sealing element 8 is arranged to isolate (sealingly separate) the second control port X2 (or a receiving chamber thereof) from the first valve bore 10, such that fluid exchange (i.e.
liquid exchange and gas exchange) is prevented between the second control port and the first bore. The seal-ing element 8 is further coupled to the second end 20. The coupling to the second end 20 is such that the sealing element is able to exert force onto the spool that effects a movement of the spool in direction of the second end position. On the other hand, the coupling to the second end 20 may be such that the sealing element is not able to exert force onto the spool that effects a movement of the spool in direction of the first end position (as shown). The coupling of the sealing element 8 to the second end 20 may be direct or indirect. In a direct coupling, the sealing element 8 to the second end 20 are in contact to achieve the coupling. In an indirect coupling (as shown), the sealing element 8 to the second end 20 are coupled by means of a coupling member 24. For example, the sealing element 8 may be coupled to the second end 20 such that the sealing element itself (direct coupling) or the coupling member 24 (indirect coupling) abuts a second (axial) face 26 of the spool near the second end 20.

4 Date Recue/Date Received 2022-12-20 The shown sealing element 8 is, for example, a membrane having a disc shape.
As shown, the sealing element 8 may be (press) fitted between the second and third valve body parts 42, 43. A first surface 14 of the membrane is configured to receive pressure from the gas, i.e. the first surface forms a barrier (or wall) of the second control port X2 (or a receiving chamber thereof), such that the pneumatic pressure received at the second control port X2 acts onto the first surface 14. A second surface 16 of the membrane 8, which is opposite to the first surface 14, is coupled to the second end 20 by means of the coupling member 24.
The coupling member 24 may have a radial protrusion 28 which extends into a recess 30 formed in the valve body. The recess is formed as recess in the first valve body part 41, for example. The axial lengths of the protrusion 28 and the recess 30 are configured such that the movement of the coupling member 24 and/or of the spool 6 in axial direction is restricted. This defines the first and the second end positions of the spool 6 as explained above. It will be appreciated by those skilled in the art that other configurations are possible to achieve a re-striction of the movement of the coupling member 24 and/or of the spool 6 in axial direction or at least in one of the two (left/right in the figure) possible axial movement directions. For ex-ample, a protrusion may be provided on the spool.
In another example, not shown, the sealing element may have the shape of a (flat) ring, e.g. a membrane having an opening in the middle. In this case the coupling to the second end could be achieved by extending the second end or the coupling element through the opening and fixing, e.g. moulding, the second end or the coupling element to a circumference of the open-ing.
According to an embodiment the valve body may include a second (internal) bore or second channel (not shown) that extends in axial direction and connects the first port A with the first control port X1. In this way the pressure of hydraulic liquid at the first port A acts as control pressure at the first control port X1 onto the first face 22.
It will be appreciated by those skilled in the art that in typical use scenario the directional control valve 22 (as shown) may be mounted to a housing (not shown), e.g. by means of threads provided on the valve body 4 (such as on the second valve body part 42). The housing, e.g. a housing body thereof, includes channels to connect the ports and control ports of the direc-tional control valve to respective ports provided on the outer surface of the housing body. In

5 Date Recue/Date Received 2022-12-20 case the pressure control valve has no second bore that connects the first port and the first control port, such a channel may be provided in the housing body, if required.
It will further be appreciated by those skilled in the art that Figure 1 is merely a non-limiting example presented for illustrative and explanatory purposes.
Figure 2 schematically shows a non-limiting exemplary system 50 that includes a pressure control valve 2 such as shown in Figure 1.
The system includes a source for pressurized air 52, e.g. an air tank or compressor. The air source 52 is connected to a pneumatic control unit 54 by a pneumatic line. The pneumatic control unit 54 may include a pneumatic control valve (not shown) which controls the flow of pressurized air from the air source 52 to a pneumatic control line 56 connected to the second control port X2 of the pressure control valve 2. The pneumatic control unit 54 and in particular its pneumatic control valve may be actuated by a user by means of a hand lever, for example.
Other actuation mechanism may be used as well, such as electric and/or electro-magnetic actuation, allowing control by an electronic controller.
The second port P (pump port) of the pressure control valve 2 is hydraulically connected to a hydraulic pump 58 by a hydraulic line. The pump 58 is configured to pump hydraulic fluid (such as a hydraulic oil) from a tank 60 into the hydraulic line (and via this hydraulic line to the second port P),. The third port T (tank port) of the directional control valve 2 is hydraulically connected to the tank 60 for hydraulic liquid.
The first port A (working port) of the directional control valve 2 is hydraulically connected to a hydraulic load, such as a hydraulic cylinder 62, a hydraulic motor (not shown), a hydraulically actuated valve (not shown) etc., by means of a hydraulic line. Especially, the pressure control valve 2 can be used as a pilot valve for a hydraulically actuated valve.
The first port A is further connected to the first control port X1 of the directional control valve 2 by a hydraulic control line 64, which may be implemented internally in the directional control valve 2 by the second bore (or channel). By this, the pressure on port A is sensed (or con-trolled) by the pressure on port X2.

6 Date Recue/Date Received 2022-12-20 In the state as shown, the spool of the directional control valve 2 is in the first position, such that the first port A is hydraulically connected to the third port T, i.e.
flow of hydraulic liquid form the hydraulic cylinder 62 to the tank 60 is possible, while no flow of hydraulic liquid from the pump 58 to the hydraulic cylinder 62 is possible. The directional control valve 2 is biased into the first position by spring 12.
By operating the pneumatic control unit 54 accordingly, flow of pressurized air from the air source 52 into the pneumatic control line 56 may be enabled, such that the pneumatic pressure at the second control port X2 increases and causes the spool 6 of the directional control valve .. 2 to move into the second position once the biasing force of spring 12 is overcome. In turn hydraulic fluid flows from the hydraulic pump 60 to the first port A and from there to the hy-draulic cylinder 62. The pressure of hydraulic fluid at the first port A and therefore in the hy-draulic control line 64 and at the first control port X1 increases until an equilibrium between, on one side, the (pneumatic) force exerted by the air at the second control port X2 and, on the other side, the sum of the forces exerted by the spring 12 and by the hydraulic liquid at the first control port X1 is reached. By regulating (or controlling) the pneumatic control unit 54 accord-ingly, the pressure of the air in the pneumatic control line 56 and therefore at the second control port X2 may be controlled. Thus, the pressure of the hydraulic fluid at the first port A supplied to the hydraulic cylinder 62 may be regulated by controlling the pneumatic control unit 54. For example, the pressure of the hydraulic liquid at the first port A may increase essentially linearly with the pressure of the air at the second control port X2.
It will be appreciated by those skilled in the art that in systems other than the system shown in Figure 2, the ports of the directional control valve 2 may be connected differently to a hydraulic pump, a hydraulic load, a hydraulic tank, and/or a pneumatic control unit.
It will also be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more specific examples thereof, but is not limited to these examples; many variations and modifications are possible, within the scope of the accompanying claims.

7 Date Recue/Date Received 2022-12-20

Claims (15)

Claims

1. A hydraulic pressure control valve with pneumatic actuation, comprising a valve body, a spool, and a sealing element;
wherein the valve body has a first bore extending in an axial direction;
wherein the valve body has a first port, a second port, and a third port, the first, second and third ports connected to the first bore;
wherein the valve body further has a first control port for sensing a hydraulic fluid and a second control port for receiving a pneumatic gas;
wherein the spool is located in the first bore and movable between a first end position and a second end position, the spool having lands, such that in the first end position the first port and the third port are connected and in the second end position the first port and the second port are connected;
wherein the spool has a first end and a second end in axial direction, wherein a first face of the spool near the first end is connected to the first control port;
wherein the sealing element is arranged between the second control port and the first bore to seal the second control port from the first bore; and wherein the sealing element is flexible, such that movement of a part of the sealing ele-ment in axial direction is possible, and is coupled to the second end, such that the sealing element is able to exert force onto the spool that effects movement of the spool in direc-tion of the second end position.

2. The pressure control valve of claim 1, further comprising a biasing element arranged to bias the spool into the first position.

3. The pressure control valve of claim 2, wherein the biasing element is a spring.

4. The pressure control valve of anyone of claims 1 to 3, wherein the sealing element is a membrane having a disc shape, wherein a first surface of the membrane is configured to receive pressure from the gas, and wherein a second surface of the membrane oppo-site to the first surface is coupled to the second end.

Date Recue/Date Received 2022-12-20

5. The pressure control valve of claim 4, further comprising a coupling member, wherein the second surface is coupled to the second end by means of the coupling member.

6. The pressure control valve of claim 5, wherein the second surface abuts a first end face of the coupling member, and/or a second face of the spool near the second end abuts a second end face the coupling member that is opposite to the first end face in axial direc-tion, in order to achieve the coupling of the second surface to the second end.

7. The pressure control valve of claim 5 or 6, wherein the coupling member has a radial protrusion extending into a recess of the valve body.

8. The pressure control valve of claim 4, wherein the second surface is directly coupled to the second end.

9. The pressure control valve of claim 8, wherein the second surface abuts a second face of the spool near the second end, in order to achieve the coupling of the second surface to the second end.

10. The pressure control valve of anyone of claims 1 to 3, wherein the sealing element is ring shaped having an opening, wherein the second end extends into the opening and is fixed to a circumference of the opening.

11. The pressure control valve of anyone of claims 1 to 3, wherein the sealing element is ring shaped having an opening, wherein a coupling member extends into the opening and is fixed to a circumference of the opening, and wherein the intermediate member is coupled to the second end.

12. The pressure control valve of anyone of claims 1 to 11, the valve body further having a second bore extending in axial direction and connecting the first port to the first control port.

13. The pressure control valve of anyone of claims 1 to 12, wherein in the first end position the first port is not connected to the second port, and in the second end position the first port is not connected to the third port.

Date Recue/Date Received 2022-12-20

14. The pressure control valve of anyone of claims 1 to 13, wherein the spool has a radial protrusion extending into a recess of the valve body.

15. The pressure control valve of anyone of claims 1 to 14, further comprising a housing, wherein the valve body is mounted in the housing.
Date Recue/Date Received 2022-12-20